2008 6.4 PSD won't rev over 1600
Strange thing occurred this morning.
Fired up the truck, let it warm up a bit, hopped in and drove away. About a half hour later (tranny and engine temp both indicated vehicle was running at normal temperature) I turned down a side street, and the truck would not accelerate. RPMs bounced between 1500 and probably 1600 no matter where the throttle pedal was. It gave the feeling of a rev limiter engaging. I pulled over, put the truck in park, tried to rev the engine, same thing, wouldn't go over 1600. Put it back in gear, no change. Also, no check engine light came on.
Finally, I shut the engine off, removed the key, put the key back in, started the truck, and problem seems to have disappeared. Again, no check engine light.
I was close to home, so I drove home normally, and the truck is in the driveway.
Any idea what's causing this?